Wind instruments are of a variety of types and typically involve a player of the instrument forcing vibrating air columns into an input opening or mouthpiece of the instrument so that the air column travels through the length of the instrument and out the bell or output opening of the instrument. Along the path length altering loops and valves may be placed, such as for trumpets, to alter the length the air column has to travel before exiting the instrument and producing sound. It has been common knowledge for centuries that air columns of differing length produce musical notes of differing pitch. An example of an instrument based upon this principle is a pipe organ. Such organs have a multiplicity of pipes of varying lengths (as well as diameters) but the length of a particular pipe (and the air column therein) does not change. Other examples include cornets and trumpets which use linearly-actuated valves and French horns which use rotary valves, all to change the note(s) produced by the instrument. In these latter examples, such note changes are by valving tubing of various lengths into or out of the air column “circuit,” thus changing the length of the air column as measured from the instrumentalist's lips or actually he rim of the mouthpiece to the bell from which sound is emitted.
The term “brass musical instrument” is used herein in its conventional usage in the art, to denote a musical instrument that defines a length of tubing, and which has at one end a “cup mouthpiece” to receive a player's lips and has at the other end a flared opening or bell from which the sound emerges or emitted. The sound is generated when a player vibrates their lips and, simultaneously, forces a vibrating air column through the mouthpiece, the length of tubing and out the bell. As is well known, such so-called “brass musical instruments,” while often being made of various metals, including brass, are also known to be made in whole or in part of other materials, including fiberglass, plastics, carbon fiber, etc.
Conventional brass musical instruments that are constructed to be at least in part chromatic, or to play notes other than those found in the harmonic overtone series of the basic flow path defined by the instrument, include mechanisms for effectively changing the length of the tubing within the instrument through which a vibrating column of air generated by the player's lips passes. By changing the length of the tubing, a different harmonic overtone series is established that allows the generation of additional notes. Conventionally, the length of tubing may be changed by either of two primary mechanisms. A first mechanism, as used in a modern trombone is through use of an easily moveable slide, through which the length of the tube may be changed as desired by the player to facilitate the playing of all notes in a scale. The second mechanism is through the use of valves, which are selectively actuated to change the length of tubing. In modern instruments, the actuation of a valve alters the flow path of the instrument to add a given length of tubing which is sufficient to lower the harmonic series a given increment, or number of notes. Some instruments may include multiple valves for adding multiple lengths of tubing to a flow path of the instrument. For example, a modern instrument that is intended to be chromatic may include three valves, wherein the first valve lowers the harmonic series, by two steps or chromatic notes, the second valve lowers the harmonic series by a single step or note, and the third valve lowers the harmonic series by 3 chromatic steps or notes.
Air flow valves having a variety of different configurations, structures and other operative features have been used on musical instruments in the brass and/or wind family for over a hundred years in order to provide the musician playing the instrument with a greater range in terms of both pitch and tonal quality. Generally speaking, such flow path selector valves, particularly of the type used with brass-wind instruments, are either of the rotary type or alternatively, are of the piston and cylinder type. In the latter category, also commonly referred to as Perinet valves, a piston is longitudinally slidable within a cylinder against a biasing force. The piston normally has both a longitudinal bore and transverse bore which enable air to be conducted along a shorter or longer path of travel, in order to selectively vary the tonal quality of the instrument. Passages formed in this type of valve are generally round in cross section, and thereby, permit free flow of air therethrough which is desirable for achieving increased sound volume and a high quality tones. The other category of air flow valves relates to rotary valves, which typically include a valve disk which is provided at its periphery with air inlets and air outlets. These air inlets and outlets are generally disposed to communicate with one another through radial passages.
Rotary valves have been in existence since around 1832. The rotary valve design has been attributed to Joseph Riedl of Vienna, Austria. The rotary valve is disc-shaped and is actuated in a rotating motion, as opposed to piston valves that are actuated linearly. Rotary valves comprise a valve disc, which is provided at its periphery with air inlets and air outlets that communicate with each other through radial or sector-like passages. Rotary valves provide for fast playing due to the short actuating stroke of the design. Although rotary valves allowed for fast play and addressed some playability issues, they have drawbacks. One problem with the traditional rotary design is that sharp edges and constrictions formed in the disc deflect the vibrating air column flowing in the air passages to such a degree that the sound volume and the quality of the tone as well as the ease with which the tone can be produced are adversely affected. For example, common disc-shaped rotary valves have pieces of tubing (those switched into and out of the circuit by the valve) fastened to the valve casing generally radially and using rather sharp bends. And the internal valve passages themselves involved some rather sharp bends. These constrictions or “convolutions” in the air flow path add additional resistance to the flowing air column and adversely affect musician's “blowing power” by limiting the maximum volume that a musician can obtain, and also undesirably affects tonal quality.
Yet another difficulty with known rotary valves is that even though the stationary tubing attached to the valve casing is circular in cross-section, the passages in the rotating valve piston are often ellipsoid (or, perhaps of some other shape) but not circular. As a result, there is an abrupt flow discontinuity where the non-circular passage and the circular tube intersect. The tonal quality of the instrument is thereby adversely affected. Such a valve is said to lack “flow tangency.” Flow tangency is achieved when the edges of two adjacent openings, e.g., a passage exit opening and the adjacent tube entry opening (or a tube exit opening and the adjacent passage entry opening), are in registry. When so configured, there is a smooth transition surface (substantially devoid of discontinuity) over which air can flow.
A widely adopted valve configuration used in many wind instruments over the past century and widely used today is the Perinet piston valve. The Périnet valve is a piston valve, named after Francois Périnet, that first came into prominence around 1838 and comprises a cylindrical casing in which a cylindrical piston is longitudinally displaced in sliding relation within the casing against a spring force for manual actuation. The piston has longitudinal and transverse bores so that the air can be conducted along a shorter or longer path for a generation of different tones. The passages are round in cross-section so that they permit of a free flow of the air column traveling therethrough; this is desirable for achieving a large sound volume and a high quality of the tone. But the long actuating stroke and the high inertia of said valves oppose a fast playing. The valve loops are arranged in such a way that the inlet tubing is positioned on a different level than the outlet tubing. The piston is held at rest by a spring, which is placed either on top (top-sprung) or below (bottom-sprung) the piston. The Périnet valve is now the standard for trumpets in most countries (except Germany and Austria where rotary type valves are more common), and is often simply called the “piston valve.”
FIGS. 1 and 2 depict cross-sectional views of a prior art Perinet valve assembly in an open or un-actuated position (FIG. 1) and in an actuated position (FIG. 2) in which parts of a piston valve are as follows: a=valve casing; b=piston; c=valve loop with slide; d=main tubing; e=port; f=touchpiece, finger tip, lever; g=valve stem; h=top valve cap; i=baluster; k=lower valve cap; I=return spring; m=guiding slot in stem/piston; n=key; and o=keyway for piston valve guide in casing. In the unactuated position of FIG. 2, the air column enters the valve assembly from a lead pipe (not shown) at inlet port 102 of the valve casing (a) and travels through the lower windway or passage formed in the piston (b) and out through main tubing (d). In the actuated position of FIG. 2, the air column also enters the valve casing (a) from the lead pipe through the same inlet port but now travels through the middle windway or passage formed in the valve piston (b) out of the valve piston and through valve loop (with slide) (c) and back into the valve assembly and travels through the upper windway or passage and exits through main tubing (d). These windways, depending on orientation and function, may be referred to as “switching” or “return” windways. A problem commonly associated with Perinet valves is that due to physical constraints associated with placing liners (or troughs or tubular material) that form the upper, middle and lower windways within the openings formed in the piston and disposing the liners within the hollow inner volume of the piston body, tradeoffs have been made that adversely affect tonal quality and volumetric capacity and laminar flow of the air column passing through the Perinet valve. In particular, the manufacturing of the piston valve due to the size constraints within the narrow hollow piston body results in “lumps” or “bumps” being formed in at least one and typically two of the windways.
With reference to the prior art valve assembly of FIGS. 1 and 2, the piston valve consists of a cylindrical outer casing (a) and the piston (b) inside, which fits tightly within the outer casing. The valve loop (c), as well as the main tubing (d), are soldered to the outer casing. The piston is perforated with ports (e) that lead the air column either straight through the main tubing or into the valve loop. The valve loop is disengaged or engaged by the up-and-down movement of the piston within the casing that aligns the ports either with the main tubing or the valve loop. Traditionally, circular in cross-section passages are provided through the valve assembly and the cross-section of the passage is preferably about the same as the bore of the windpipes or passages. Accordingly, the casing and piston of the valve assembly are fabricated to conform in size and shape cross-sectionally to the windpipes. This results in less than generous space in the valve piston in which to form switching and return passages. Another common consideration in the design of piston valves is the desire to make the actuation stroke as short as possible to enhance speed of play. Unfortunately, this leads to the drawback of further constricting the amount of space available for forming the windways or passageways in the piston body.
For example, FIG. 3 depicts an elevation view of a prior art Perinet valve piston with valve casing in cross-section as disclosed in U.S. Pat. No. 1,112,120 (Conn) entitled Cornet-Valve. As shown in the figure, lumps 302 are formed in the middle “port” 3 formed transversely through the piston valve 2. As stated above, the goal is to provide a circular in cross-section windway through which air columns travel so as to minimize deflection and interruption of the air column. Harmonics also play a role in the configuration of the valve, valve loop, etc. Lumps formed as an artifact in the manufacturing process represent irregularities in the surface of the windway and cause distortion in the air column passing through the windway. In order to provide the shortest actuation stroke possible, the windways are brought together as close as possible and the size of the windways is restricted. This has the unfortunate effect of increasing the severity of the lumps and limiting the volumetric capacity and flow of the valve. What is needed is a valve piston design that removes or minimizes the lumps resulting from manufacturing the windways and increases volumetric flow capacity. What is also needed is a method of manufacturing valve pistons that address these problems while providing structural integrity and stability.
Accordingly, there is a need in the musical industry for an improved flow regulating valve assembly for use on a musical instrument such as, but not limited to, a brass type of wind instrument.